Question: Umaima is 4 times as old as Ashley and is also 15 years older than Ashley. How old is Umaima?
Explanation: We can use the given information to write down two equations that describe the ages of Umaima and Ashley. Let Umaima's current age be $u$ and Ashley's current age be $a$ $u = 4a$ $u = a + 15$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $u$ is to solve the second equation for $a$ and substitute that value into the first equation. Solving our second equation for $a$ , we get: $a = u - 15$ . Substituting this into our first equation, we get the equation: $u = 4$ $(u - 15)$ which combines the information about $u$ from both of our original equations. Simplifying the right side of this equation, we get: $u = 4u - 60$ Solving for $u$ , we get: $3 u = 60$ $u = 20$.